Question 1

Injection lasers operating in smaller wavelengths are subjected to increased carrier losses.

Accepted Answer

A) True 
 B)False  False

Question 2

The diode-cladding-pumped Erbium praseodymium-doped fluoride device operates at wavelength.

Accepted Answer

A)  around 3 ?m
B)  4 ?m
C)  2.6 ?m
D)  1.04 ?m A

Question 3

Lasing obtained in __________ when 191 mW of pump light at a wavelength of 0.477 ?m is launched into laser.

Accepted Answer

A)  ternary pbsnsete alloy laser
B)  quaternary pbsnsete alloy laser
C)  doped fluoro-zirconate fiber
D)  ternary pbeute alloy laser C

Question 4

Fiber based lasers provide diffraction-limited power at higher levels than solid-state laser. State whether the given statement is true or false

Accepted Answer

A) True 
 B)False

Question 5

The absence of _______________ in LEDs limits the internal quantum efficiency.

Accepted Answer

A)  proper semiconductor
B)  adequate power supply
C)  optical amplification through stimulated emission
D)  optical amplification through spontaneous emission

Question 6

How many sections are included in a sampling grating distributed Bragg-reflector laser (SG-DBR)?

Accepted Answer

A)  four
B)  five
C)  three
D)  two

Question 7

The mechanism which results from a refractive index change in the passive waveguide layer is called as

Accepted Answer

A)  absorption
B)  spontaneous emission
C)  monolithic inversion
D)  bragg wavelength control

Question 8

In a junction diode, an equilibrium condition occurs when

Accepted Answer

A)  ?ngreater than ?p
B)  ?nsmaller than ?p
C)  constant current flow
D)  optical amplification through stimulated emission

Question 9

The parameters having a major role in determining threshold current of efficiency of injection laser are:

Accepted Answer

A)  angle recombination and optical losses
B)  frequency chirping
C)  relaxation oscillation
D)  mode hopping

Question 10

In a QC laser, a same electron can emit number of photons.

Accepted Answer

A) True 
 B)False

Question 11

In QC lasers, it is possible to obtain different output signal wavelengths. This can be achieved by

Accepted Answer

A)  inter-valence band absorption
B)  mode hopping
C)  quantum cascading
D)  selecting layers of different thickness

Question 12

The thulium doped fiber laser when pumped with alexandrite laser output at 0.786 ?m, the laser emits at

Accepted Answer

A)  0.6 ?m
B)  0.8 ?m
C)  2.3 ?m
D)  1.2?m

Question 13

A technique based on inter-sub band transition is known as

Accepted Answer

A)  auger recombination
B)  frequency chirping
C)  inter-valence band absorption
D)  quantum cascading

Question 14

A QC laser is sometimes referred as:

Accepted Answer

A)  unipolar laser
B)  bipolar laser
C)  gain guided laser
D)  non semiconductor laser

Question 15

Replacing Sn with Eu, Cd or Ge in some _________________ the band gap.

Accepted Answer

A)  remove the band gap
B)  does not affect
C)  decreases
D)  increases

Question 16

The lasing line-width of Fox-smith resonator is ____________________

Accepted Answer

A)  less than 1 mhz
B)  1 mhz
C)  2 mhz
D)  greater than 3 mhz

Question 17

Determine the total carrier recombination lifetime of a double heterojunction LED where the radioactive and nonradioactive recombination lifetime of minority carriers in active region are 70 ns and 100 ns respectively.

Accepted Answer

A)  41.17 ns
B)  35 ns
C)  40 ns
D)  37.5 ns

Question 18

The phenomenon resulting in the electrons to jump from one state to another each time emitting of photon is known as :

Accepted Answer

A)  inter-valence band absorption
B)  mode hopping
C)  quantum cascading
D)  quantum confinement

Question 19

The hole concentration in extrinsic materials is _________ electron concentration.

Accepted Answer

A)  much greater than
B)  lesser than
C)  equal to
D)  negligible difference with

Question 20

An MQW cascaded laser is more advantageous because of:

Accepted Answer

A)  mode hopping
B)  auger recombination
C)  control over layers of material
D)  properties of material

Exam 16: Laser Technology and Devices